The invention relates to an electrical protection circuit breaker which is responsive to overload current, to short circuit current and to earth leakage current. The circuit breaker includes a structural and functional combination of one or several single pole interrupting circuit breakers (LS-circuit breaker) with an earth leakage current circuit breaker (FI-circuit breaker) whereby the circuit breaker elements which are to be combined, are respectively constructed in a compact or narrow manner and with the same housing contour.
Such "full protection circuit breakers" serve simultaneously for the protection of the conductor network to be monitored against short circuiting and against overloading as well as for preventing of electric accidents due to conductor defects and the like. The basic construction of these circuit breakers is known, for example, from German Patent No. 1,169,015. However, the protection circuit breaker described in said German Patent requires an expensive internal wiring which is subject to a high dissipation loss for the LS-circuit breaker member through the summing current transformer of the FI-circuit breaker member and from there back again. Thus, this known circuit cannot be constructed for multi-pole circuit interruption. Further, it is necessary that the contact mechanism of the FI-circuit breaker member must be mechanically actuated by the locking cam of the LS-circuit breaker member. This "feedback" from the FI-circuit breaker magnet through the LS-locking cam back to the FI-contact mechanism is due to the lack of space inside the FI-circuit breaker housing having the same contour and constructed in a compact manner. This is so because already the summing current transformer, the breaker magnet, and the testing device do not leave any space in the housing for the installation of its own circuit interrupting member.
Due to this the practice has turned to constructing the FI-circuit breaker member without its own contact interruption point, said FI-circuit breaker member being coupled in the same housing widths and contour with an LS-circuit breaker member which provides a single pole circuit interruption. In the alternative, where the FI-circuit breaker member is provided with its own breaker and interrupting mechanism and coupled with multi-pole LS-circuit breaker components, the FI-circuit breaker member is wired initially ready for mounting inside and outside of the common housing, (German Patent Publication No. 1,563,827 and German Patent Publication No. 2,756,237). These protective circuit breakers, however, have the disadvantage that the first mentioned type interrupts the load current circuit unpermissibly only in a single pole manner, whereby the apparatus becomes practically ineffective when a mix-up of poles occurs or when the third conductor is hot. The second mentioned structure does not involve this danger. However, instead the FI-circuit breaker member is twice as broad in space as the first mentioned structure. In addition, the dissipation power of the entire circuit breaker is substantially higher due to the involved inner wiring.